Supersensitized photographic emulsions containing un-ionized dyes



March 22,' 1955 Q H, CARROLL ETAL 2,794,715

SUPERSENSITIZED PHOTOGRAPHIC EMULSIONS CONTAINING UNIONIZED DYES Filed Jan. l5, 1954 FIGZ.

Hwrm ml www-WW WIWI 30o 400 500 600 700 D 3, 3 /METHYL 9- PHENYL- 4,5, 415'- /BfNzorHMcAMocrAN/NE BROMIDE ARB/TuR/c Ac/D BURT H. CARROLL JEAN E. JONES JNVENTORS United States Patent O l 2,704,715 SUPERSENSITIZED PHOTOGRAPHIC EMULSIONS CONTAINING UN-IGNIZED DYES Burt H. Carroll and Jean E. Jones, Rochester, N. Y., as-

signors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application January 13, 1954, Serial No. 403,879 16 Claims. (Cl. 95-7) This invention relates to photographic emulsions containing cyanine dyes, and in supersensitizing combination, certain un-ionized dyes.

It is known in the art of making photographic emulsions that certain dyes of the cyanine class alter the sensitivity of photographic emulsions of the gelatino-silverhalide kind, when the dyes are incorporated in the emulsions. It is also known that the sensitization produced by a given dye varies somewhat with the type of emulsion in which the dye is incorporated. Furthermore, the sensitization of a given emulsion by a given dye may be altered by varying the conditions in the emulsion. For example, the sensitization may be increased by increasing the silver ion concentration or decreasing the hydrogen ion concentration (i. e. increasing the alkalinity) or both. Thus, sensitization can be increased by bathing plates, coated with a spectrally sensitized emulsion, in water or in aqueous solutions of ammonia. Such a process of altering the sensitivity of a sensitized emulsion by increasing the silver ion concentration and/or by decreasing the hydrogen ion concentration is commonly called hypersensitization. Hypersensitized emulsions have generally poor keeping qualities.

We have now found a new means of altering the sensitivity in emulsions containing cyanine dyes. Since the conditions in the emulsion, i. e. the hydrogen ion and/ or the silver ion concentration undergo little or no change in our method, we shall designate our new method as a kind of supersensitization.

It is, therefore, an object of our invention to provide photographic emulsions containing cyanine dyes, and in supersensitizing combination therewith, certain un-ionized dyes. Another object is to provide a process for preparing these supersensitized emulsions. Other objects will become apparent from a consideration of the following description and examples.

The cyanine dyes useful in practicing our invention can advantageously be represented by the following general formula:

I Z Rz 2,704,715 Patented Mar. 22, 1955 the naphthothiazole series (e. g. a-naphthothiazole, -naphthothiazole, 7-methoXy-a-naphthothiazole, Stmethoxy-a-naphthothiazole, S-methoxy ,B naphthothlazole, 5-ethoxy-a-naphthothiazole, etc.), a heterocyclic nucleus of the benzoselenazole series (e. g. benzoselenazole, 5 chlorobenzoselenazole, 6 methoxybenzoselenazole, 5-methoxybenzoselenazole, etc.), a heterocyclic nucleus of the naphthoselenazole series (e. g. a-naphthoselenazole, I-naphthoselenazole, etc.), a heterocyclic nucleus of the benzoxazole series (e. g. benzoxazole, 5-hydroxybenzoxazole, -hydroxybenzoxazole, 5-chlorobenzoxazole, 5-methoxybenzoxazole, -methoxybenzoxazole, 5-phenylbenzoxazole, S-bromobenzoxazole, etc.), a heterocyclic nucleus of the naphthoxazole series (e. g. a-naphthoxazole, -naphthoxazole, etc.), a heterocyclic nucleus of the Z-quinoline series (e. g. 2-quinoline, 6-methyl-2-quinoline, 7-methyl-2-quinoline, 8-methyl-2-quinoline, 6-chloro-2- quinoline, 8-chloro2-quinoline, 4-chloro 2 quinoline, S-ethoxy-Z-quinoline, 6-ethoxy-2-quinoline, 7-ethoxy-2- qunoline, 6-hydroXy-2-quinoline, 7-hydroxy-2-quinoline, -rnethoxy-Z-quinoline, etc.), a heterocyclic nucleus of the 4-quinoline series (e. g. 4-quinoline, -methoxy-Lquinoline, 7-methyl-4-quinoline, 8-methy1-4-quinoline, etc.), etc.

The un-ionized dyes useful in practicing our invention can advantageously be represented by the following general formula:

wherein Rs and R4 each represents an alkyl group i. e. an alcohol radical, e. g. methyl, ethyl, n-propyl, n-butyl, -hydroxyethyl, carbethoxyrnethyl, benzyl (phenylmethyl), etc., Q represents the non-metallic atoms necessary to complete an indandione nucleus or a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, such as those of the pyrazolone series (e. g. 3-methyl-1- phenyl-S-pyrazolone, l-phenyl-S-pyrazolone, l-(2-benzothiazolyl-3-methyl-S-pyrazolone, etc.), those of the isoxazole series (e. g. 3-phenyl-5-(4H), isoxazolone, 3-methyl- 5(4H) isoxazolone, etc.), those of the indandione series (e. g. 1,3-diketohydrindene, etc.), those of the oxindole series (e. g. 1-alkyl-2,3-dihydro-Z-oxindoles, etc.), those of the 2,4,6-triketohexahydropyrimidine series (e. g. barbituric acid or Z-thiobarbituric yacid as well as their l-alkyl (e. g. l-methyl, l-ethyl, 1-npropyl, l-n-heptyl,

wherein R and R1 each represents an alkyl group, such as methyl, ethyl, n-propyl, carbethoxymethyl, etc., R2 reprea sents an aryl group, such as phenyl, o, m, and ptolyl, o, rn, and p-chlorophenyl (e. g. a mononuclear aromatic group of the benzene series), a-naphthyl, -naphthyl, 9-phenanthryl, etc., or a pyrryl group (simple or condensed nucleus), such as pyrryl, indolyl, pyrrocolyl, benzoindolyl, etc., m and n each represents a positive integer of from l to 2, X represents an acid radical, such as chloride, iodide, bromide, perchlorate, p-toluenesulfonate, benzenesulfonate, ethylsulfate, methylsulfate, etc., and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, e. g. a heterocyclic nucleus of the thiazole series (e. g. thiazole, 4 methylthiazole, 4 phenylthiazole, 5 methylthiazole, 5-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, etc.), a heterocyclic nucleus of the benzothiazole series (e. g. benzothiazole, 4chlorobenzothiazole, 5chlo robenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazo1e, 5-methylbenzothiazole, 6-methylbenzothiazole, 5bromobenzothiazole, 6-brornobenzothiazole, 4-phenylbenzothiazole, 5-phenylbenzothiazole, 4-methoxybenzothiazole, S-methoxybenzothiazole, 6-methoxybenzothiazole, -iodobenzothiazole, 5-iodobenzothiazole, 4-ethoxybenzothiazole, S-ethoxybenzothiazole, 5,6 dimethoxybenzothiazole, 5 hydroxybenzothiazole, -hydroxybenzothiazole, etc.), a heterocyclic nucleus of etc.), or 1,3-dialkyl (e. g. 1,3-dimethyl, 1,3-diethyl, 1,3- di-n-propyl, 1,3-diisopropyl, 1,3-dicyclohexyl, l,3-di( methoxyethyl), etc.), or 1,3-diary1 (e. g. 1,3-diphenyl, l, 3-di(pchlorophenyl) 1,3-di( p-ethoxycarbonylphenyl) etc), or 1-aryl (e. g. lphenyl, l-p-chlorophenyl, 1-pethoxycarbonylphenyl), etc.) or 1-alkyl-3-aryl (e. g. l-ethyl-3-phenyl, l-n-heptyl-S-phenyl, etc.) derivatives, those of the rhodanine series (i. e. 2-thio-2,4thazolidine dione series) such as rhodanine, 3-alkylrhodanines (e. g. 3-ethylrhodanine, 3-allylrhodanine, etc.) or 3-arylrhodanines (e. g. 3-phenylrhodanine, etc.), etc., those of the 2(3H)-imidazol,2apyridone series, those of the 5,7- dioxo-6,7-dihydro-5-thiazolo 3,2-a-pyrimidine series (e. g. 5,7-dioxo 3 phenyl-6,7-dihydro-5-thiazole 3,2-a-pyrimidine, etc.), those of the 2-thio-2,4oxazolidinedione series (i. e. those of the 2-thio2,4(3H,5H) -oxazoledione series) (e. g. 3-ethyl-Z-thio-2,4oxazolidinedione, etc.), those of the thianaphthenone series (e. g. 2(3H)thianaphthenone, etc.), those of the 2-thio-2,S-thiazolidinedione series (i. e. the 2thio-2,5(3H,5H)thiazoledione series) (e. g. 3-ethyl- 2-thio-2,S-thiazolidinedione, etc.), Z2 represents the nonmetallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, e. g. a heterocyclic nucleus of the benzothiazole series (e. g. benzothiazole, 4-chlorobenzothiazole, S-chlorobenzothiazole, -chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenzothiazole, 6-methy1benzothiazole, S-bromobenzothiazole, -bromobenzothiazole, 4-phenylbenzothiazole, 5-phenylbenzothiazole, 4-methoxybenzothiazole, S-methoxybenzothiazole, 6-methoxybeuzothiazole, 6-iodobenzothiazole, 5-iodobenzothiazole, 4ethoxybenzothiazole, S-ethoxybenzothiazole, 5,6-dimethoxybenzothiazole, hydroxybenzothia zole, -hydroxybenzothiazole, 7-hydroxybenzothiazole, etc.), a heterocyclic nucleus of fthe naphthothiazole series (e. g. a-naphthothiazole, -naphthothiazole, 7-methoxya-naphthothiazole, S-methoxy--naphthothiazole, 5-methoxy--naphthothiazole, 5-ethoXy-a-naphthothiazole, etc.), a heterocyclic nucleus of the benzoselenazole series (e. g. benzoselenazole, 5-chlorobenzoselenazole, -methoxybenzoselenazole, S-methoxybenzoselenazole, etc.), a heterocyclic nucleus of the naphthoselenazole series (e. g.

more of the cyanine dyes selected from those represented by Formulas I or III above with one or more of the dyes selected from those represented by Formulas II or IV above in a photographic emulsion. Our invention is particularly directed to the ordinarily employed gelatinosilver-halide emulsions. However, our supersensitizing combinations can be employed in silver halide emulsions in which the carrier is other than gelatin, e. g., a resinous substance or cellulosic material which has no deteriorating eiect on the light-sensitive materials.

The sensitizing dyes can be employed in various concentrations depending upon the eiects desired. As is well known in the art, the sensitivity conferred upon an emulsion by a sensitizing dye does not increase propora-naphthoselenazole, ,B-naphthoselenazole, etc.), a heterotionately to the Concentration of the dye in the emulsion, cyclic nucleus of the naphthoxazole series (e. g. -naphbut rather passes through a maximum as the concentrathoxazole, -naphthoxazole, etc.), etc. andZs reprsents the tion is increased. In practicing our invention, the innon-metallic atoms necessary to complete a heterocyclic dlyldnal SensitlZlng dyes are advantageously employed in nucleus of Ithe naphthothiazole series (such as those a concentration somewhat less than their optimum conlisted above for Z2) or the naphthoselenazole Series (such 20 Centr 3.11011 (l. e. h COHCCIll'aIOll at Which the as those listed above for Z2), dyes give greatest sensitivity). If each of the dyes in Cyanine (i. e. carbocyanine) dyes represented by the supersensitizing combination is employed in its op- Formula I above wherein R2 represents a pyrryl nucleus tlmum Concentration, it is possible, in certain cases that include dyes represented by the following general the sensitization produced by the supersensitizing comformula; bination will have passed through a maximum.

m u fzi" iz-'(-on=on).,l n o=on-o(=oH-GH).1=`N-R1 wherein R, Ri, X, Z, Z1, m and n each has the values The optimum concentration of an individual sensitizgiven above, R5 and Re each represents a hydrogen atom, ing dye can be determined in a manner well known to an alkyl group, such as methyl, ethyl, n-propyl, n-amyl, those skilled in the art by measuring the sensitivity of a n-heptyl, n-dodecyl, cyclohexyl, etc. or an aryl group, Series of t es t portions of the same emulsion, each porsnch as phenyl, Q m, and p-tolyl, etc., and R5 and R6 40 tion containing a different concentration of the sensitiztogether can represent the non-metallic atoms necessary lng dye- The optimum concentration of our supersensito complete a heterocyclic nucleus of the pyridine series, tlZlng Comblnations een, of Course, be readily determined and Z4 represents the non-metallic atoms necessary to 1n the saine manner, by measuring the sensitivity of a complete a pyrrole nucleus (includes simple or conseries of test portions of the same emulsion, each pordensed pyrrole nuclei, e. g. pyrrole, indole, pyrrocoline, tion containing diterent concentrations of the individbenzoindole, etc.). The dyes represented by Formula Ual dyes 1n the Combination ln determining the IH above have been previously described in the copend- O Ptlmnnl Concentration for the supersensitizing combinaing application, U. S. Serial No. 267,928, led January tion, 1t is adyanfageous to employ, at first, CorlCentrationS 23, 1952, in the names 0f Donald W, Heseltine and r of lthe individual dyes less than their optimum concen- Leslie G, S, Brooker, now Patent Nd 2,666,761 of "o trations. .The concentrations of the individual dyes can January 19, 1954. then be increased until the optimum concentration of Dyes of Formula II above which have been found to the snpereensltiling Combination S determined. be particularly useful in practicing our invention include O rdlnarlly the optimum 0I' near optimum Coneentradyes selected from those represented by the following 5,. tratlon of the eyanlne (ie- Carboeyanine) dyes Selected general fol-mma; 0 from those represented b y Formula I (or Formula III) Iv s above, which we employ in practicing our invention, is of IZ,` the order of from 0.05 to 0.3 g. per mol. of silver halide in the emulsion. C=CH"C=CH" g-R e0 The un-ionzed dyes selected from those represented l by Formula II (or IV) above are advantageously em- N ,f e ployed in concentrations on the order of from .05 to 3.3 Q" "CO g. per mol. of silver halide in the emulsion.y

Generally speaking, the ratio of concentration of the dye of Formula II or IV to the cyanine dye of Formula wherein R3, R4, Z3 and Q each have the vaiues given I (0r III) can vary rather wldely in our combinations. above. Particularly useful are those dyes wherein Q egfrom 1320 to 3l by Welglltln manycases. represents the non-metallic atoms necessary to complete The, methods 0f incorporating s ensltrzlng dyes 1n a heterocyclic nucleus of the barbituric acid series and Z3 emulsions are v lell known to those .skilled in the art. In represents the non-metallic atoms necessary to complete Practlolg 0111 1I1Ve11i1011, tl1e 56351D2133 'dyes Carl be lna heterocyclic nucleus of the naphthothiazole series or orporaied 1n i-lle emulsions separately o 1' ogeihen It the naphthosdenazole seriesis convenient to add the dyes separately in the form of Many of the dyes represented by Formula I above solutions in appropriate s olvents. MethanoL ethanol, wherein R2 represents an aryl nucleus have been pre- Pyrldlne, etc- (and esPeClallY Pyrldlrle) have Proven viously described in the prior art. See, for example, Satisfactory as solvents for the dyes of Formulas I, Il, III U. S. Patents 1,934,659 (dated November 7, 1933), 0r IV which we employ. Acetone has also been found 2,107,379 (dated February 8, 1938), 2,112,140 (dated to be a suitable solvent in certain cases. Pyridine has March 22, 1938), 2,369,646 (dated February 20, 1945)s been found to be a particularly eicacious solvent, in 2,369,657 (dated February 20, 1945), 2,486,173 (dated that an enhanced supersensitizing effect is demonstrated October 25, 1949), and 2,515,913 (dated July 18, 1950). in certain cases when pyridine is employed. It has also The dyes of Formula II (or IV) are described in the been noted that while certain of the dyes of Formula copending applications Serial No. 282,696, filed April 16, II (or IV) have only a slight sensitizing action (or no 1952 (now abandoned), and Serial No. 375,279, filed detectable action) when used alone, when the dyes of August 19, 1953, of Leslie G. S. Brooker and F. L. FormulaII (or IV) are used in conjunction with pyridine White. a noticeable increase in speed is observed. Pyridine is According to our invention, we incorporate one or not essential to successful operations according to our invention, however. In general, it is advantageous to employ pyridine, diluted with methanol or acetone, as the solvent for the supersensitizing combinations of our invention. For example, the dye can be dissolved in pyridine and the solution then diluted with methanol or acetone. The dyes are advantageously incorporated in the finished, washed emulsions and should be uniformly distributed throughout the emulsions. The following procedure is satisfactory: Stock solutions of the sensitizing dyes desired are prepared by dissolving the dyes in appropriate solvents as described above. Then, to the owable gelatino-slver-halide emulsion, the dcsired amounts of the stock solution of one of the dyes are slowly added, while stirring the emulsion. Stirring is continued until the dye is thoroughly incorporated in the emulsion. Then the desired amount of the stock solution of the second dye is slowly added to the emulsion, while stirring. Stirring is continued until the second dye is thoroughly incorporated. The supersensitized emulsion can then be coated out on a suitable support, such as glass, cellulose derivative film, resin lm, or paper, to a suitable thickness and allowed to dry. The details of such coating methods are well known to those skilled in the art.

The amounts of the individual sensitizing dyes actually incorporated in the emulsion will vary somewhat from dye to dye, according to the emulsion employed and according to the effect desired. The regulation and adoption of the most economical and useful proportions will be apparent to those skilled in the art upon making the ordinary observations and tests customarily employed in the art. Accordingly, the foregoing procedure and proportions are to be regarded only as illustrative. Clearly our invention is directed to any emulsion containing a combination of the aforesaid sensitizing dyes whereby a supersensitizing eiect is obtained.

The following examples will serve to illustrate further the manner of practicing our invention. To diierent portions of the same batch of photographic gelatinosilver-bromiodide emulsion Were added (l) a cyanine dye selected from those of Formula I (or III) above and (2) a combination of the cyanine dye of Formula I (or Cil III) and an un-ionized dye selected from those represented by Formula II (or IV) above. In some instances, a third coating was prepared using the same emulsion formula and adding only one of the un-ionized dyes selected from those of Formula II (or IV). In some instances, the table will show that this third coating gave only a low speed or one too low to measure in the region transmitted by the filter (designated asterisk in the table). Dierent emulsions were used in some of the examples, although the emulsions of each individual example were obtained from the same batch. However, the coatings of Examples l, 2, 3 and 4 were obtained from the same batch of emulsion. The coatings of Examples 5, 6 and 7 were obtained from the same batch of emulsion, the coatings from Examples 8, 9 and l0 were obtained from the same batch of emulsion, the coatings of Examples 14, l5, 16 and 17 were obtained from the same batch of emulsion, the coatings of Examples 18 and 19 were obtained from the same batch of emulsion, the coating of Examples 21-28 were obtained from the same batch of emulsion, the coatings of Examples 29-34 were obtained from the same batch of emulsion, the coatings of Examples 35, 36 and 37 were obtained from the same batch of emulsion, and the coatings of Examples 38, 39 and 40 were obtained from the same batch of emulsion. The coatings of Examples 1-10 and 13-20 contained 20 cc./mol. AgX of pyridine, while the coatings of Examples 2l, 22, 23, 25, 27, and 29-40 contained 30 cc./mol. AgX of pyridine. Before coating, the emulsions were digested for a short time in a tank maintained at 52 C. The diierent portions of emulsion were then coated on supports and exposed in the usual manner in a spectrograph and a sensitometer (Type Ib) through a Wratten No. 25 ilter, i. e. a filter which transmits substantially no light of wavelength shorter than 580 mu, and/or a Wratten No. 12 filter, i. e. a lter which transmits substantially no light of wavelength shorter than about 495 mu (except for about 1% between 300 and 340 mu), and the exposed emulsions developed in the usual manner. The speed (red and/ or minus blue), gamma and fog for each of the coatings was determined. The results are recorded in the following table.

Red Light Minus Blue Exposure Exposure Ex. Dye (g./mol. AgX) F 0 G 10/i 10/i Speed Gamma Speed Gamma (a) 1,3Diethyl-5[di(1-ethyl-2(1H)--naphthothiazolglidene) isopropylidene1barbi- 9. 0 1. 72 05 1 tun'c acid (0.040).

(b) 3,3'-Diethyl-Q-phenylthiaearbocyanine iodide (0.080) ------.-.-...f.-... 7. 6 3. 12 05 (c) dye (a) (0.020) plus dye (b) (0.080)-- 25. 5 3.07 .05 2 {(d) 3,3-Diethy19phenylselenacarbocyanine bromide (0.080) 6. 8 2. 79 05 (e) dye (a) (0.020) plus dye (d) (0.080) 27.0 3.02 .05 3 {(f) 3,3'Dimethyl-9-pheny1-4,5,4',5-dibenzoselenacarhocyanine bromide (0.080)- 6. 2 2.92 .05 (g) dye (a) (0.020) plus dye (j) (0.080 31.0 2.82 .06 4 {(h) 3,3Dimethyl9phenyl4 5,4',5dibenzoselenathiacarbocyanine iodide (0080).- 3.9 2.49 .05 (i) dye (a) (0.020) plus dye (h) (0.080) 22.0 2.87 .06 (j) 3,3Dimethyl9phenyl4,5,4,5'dibenzothianarboeyanine bromide (0080).. 13. 5 3. 00 07 5 (k) dye (a) (0.020) 7.1 1.76 .05 (l) dye (j) (0.080) plus dye (a) (0.020) 52.0 3.02 .07 {(m) 1Etly5l2c (1ethyl-2(1H) --naphthothiaz olylidene) isopropylideue]barbituric 05 6 aci (n) dye (i) (0.080) plus dye (m) (0.020) 44.0 3.20 .07 (o) 5-[(3Ethyl-2(3H) -a-naphthothiazolylidene) (1-ethyl-2(1H)-maphthothia- 6.6 2.68 .05 7 zolylidene)isopropylidene]-1-methyl-2-thiobarbituric acid (0.020).

(p) dye (j) (0.080) plus dye (o) (0020).--- 29. 5 3. 48 .07 (q) dye (j) (0.080) 11. 8 3. 28 .07 8 (r) 1,3Diethyl-5[(3ethyl2(3H)-benzothiazolylidenel (l-methyl-2(lH)-naphtho 9. 2 3. 24 .05

"" selenazolylidene) isopropylidene12thiobarbituric acid (0.020).

(s) dye (j) (0.080) plus dye (r) (0.020) 24.0 3. 32 .07 (t) 5-[(3Ethyl2(3H) -benzothiazolylideue) (3-ethyl2(3H)-a-naphthothiazolyli- 6.6 2.12 04 9 dene)isopropylidene]-1-1netl1y1-2-thiobarbitiu'ic acid (0.020).

(u) dye (j) (0.080) plus dye (t) (0.020) 16. 5 2.74 .07 (17) 5-[Di(1-ethyl2(1H)-B-naphthothiazolylidene)isopropylidene] -1-1uethyl-2-th1o- 6. 3 1. 7 04 10.--.. barbituric acid (0.020).

(w) dye (j) (0.080) plus dye (v) (0.020) 18. 5 3.10 .07 (I) dye (j) (0.080) 10.2 2.84 .06 (1l) 2- [(lgethyl- 2(1H) -Bnaphthothiazolylidene) lsopropylidene] 1,3 mdandione 3. 0 1. 84 06 11.----

(z) dye (j) (0.080) plus dye (y) (0.020) 38. 0 2. 80 06 (a) dye (j) (0040)-. 7.6 2.68 .06 12 (b) 4-[Di(1-ethyl-2(1H) -naphthothiazolylidene) isopropylidene] -3-phenyl-5(4H) 06 isoxnzolone (0.080).

(c) dye (j) (0.080) plus dye (b) (0040)-- 27.0 2. 60 .08 (d) dye (j) (0. 8 11.0 2.8 .07 13-.--- (e) dye (b') (0.040) 21. 5 3. 24 .06 (j) dye (j) (0.080) plus dye (b) (0.020) 30.0 2.67 .0S (g') 9-(1-Ethyl-2,5-dirnethyl-B-pyrryl)-3,3dimet:hylv 4',5d1benzoth1acarbocya .07 14 nine iodide (0.080).

(h) dye (a) (0.020)-- .05 dye (g') (0.080) plus dye (a) (0.020) i .07 j (j') 3,3 Diethyl 9 (1 ethyl- 2,5 dimethyl-B-pyrryl) 4,5,4',5d1benzothxacarbocya 07 15.--.. nine iodide (0.080).

),(k') dye (a) (0.020) plus dye (j) (0.080) .07

Red Light Minus Blue Exposure Exposure Ex. Dye (gJmol. AgX) F G Sig/eid Gamma Sgd Gamma 16 [(Z') 9-(B-Indolyl)-3,3'dimethyl-4,5,4,5'-dibenzothiarbocyanine iodide (0.080) 23. 0 3. 14 06 (m) dye (Z) (0.080) plus dye (a) (0.020) 42. 0 3. 08 .07 (n') 3,3'Dimthyl-9- (2 -fmet1yg-6,7-yenzo--indolyl)-4,5,4,5dibcnzothiacarbooya 22. 5 3. 12 07 nme-po nene-su ona e 0.080

(0') dye (11') (0.080) plus dye (a) (0.020) 31.0 3.32 .07 (p') dye (a) (0.020) .06 18---.- (Q0 3,3Dimethyl9(3pyrryl)-4,5,4,5'dibenzothiacarbocyanine bromide (0080).... 16. 0 3.44 .06 (r) dye (q) (0.080) plus dye (a) (0.020). 47.0 2. 62 06 19 {(a) 3,3Dimethyl9(3pyrryl)-4,5,4,5dibenzoselenacarbocyanme bromide (0.080) 11. 0 3. 09 05 (t) dye (s) (0.080) plus dye (a) (0.020) 31.0 2. 86 .06 (u) B-Ellyl-'ietlybd(2-methyl-3-indolyl)-4',5,6,7-dibenzooxaearbocyanine per- .04

c ora e 2 (0') aye (y) (0.08m 10.0 1. 54 .o5 (w') dye (1 1') (0.080) plus dye (y) (0040)--.. 17.0 1. 30 .05 (x) dye (J) (0.080) 4. 9 2.87 6. 2 2. 87 .04 21 (y') 1,3-Diethyl 5 [(1-Ethyl-2(1H) p3 naphthothiazolyhdene) (1-methy1-2(1H) 7. 1 2. 85 7. 6 3. 1 04 naphthothazolylidene) isopropylidene]barbituric acid (0.080).

(z') dye (j) (0.080) plus dye (y') (0.020) 28.0 2. 5 32.0 2.72 .05 (a") [D 1 (1-e thy1-2(1H)--naphthothxazolylldene)lsopropyl1dene]1nheptylbarb1 20. 0 1. 9 28. 0 2. 10 06 22.-. tune acid (0.080).

(b") dye (j) (0.080) plus dye (11") (0020)-- 42.0 2.85 48.0 3.05 .05 (c) 5 [D:(1-ethyl-2(1H)--naphthothlazolylidene)lsopropylldene] 1,3d1(methox 10. 2 1. 0 10. 2 0. 81 05 23.---. yethyDbarbiturie acid (0.080).

(d") dye (j) (0.080) plus dye (c) (0.020) 40.0 2. 86 40.0 3.5 .05 (e") dye (i) (0.080) 5. 2 2. 58 5.4 3. 1 03 24.-.-- gf') dye (c") (0.080) 04 0") dye (j) (0.080) plus dye (c) (0.020) 31.0 2. 70 35. 5 3.0 .05 (h") 5 [Di(1ethyl-2(1H)--naphthothiazolylidene)lsopropylldene] l-n-heptyl 3 31. 0 1. 92 40. 0 2. 1 05 25--..- phenylbarbitm'ic acid (0.080).

dye (j) (0.080) plus dye (11") (0.020)-- 50.0 2.8 47. 0 3. 2 .05 26 (1") dye (h 0.080 .04 (k") dye (j) (0.080) plus dye (11") (0.020). 25. 5 2.88 31.0 3.0 .05 27 (1") 1,3 ;D;: yclqhexy 0508.[)(1ethyl2(1H)-naphthothiazolyhdene)xsopropylldene] 5. 8 1. 26 7. 1 1. 72 05 ar 1 une aci (1'1") dye (j) (0.080) plus dye (1") (0.020) 45.0 3. 08 50.0 2.86 05 28 I (11) dye l 0.080 .05 (0) dye (j) (0.080) plus dye (1") (0.020) 25.5 3.2 29.0 3.2 .05 (11) dye (a) (0.040)- 6.3 1.18 .05 29.---- (q") 1,1'Dimethy110phenyl2,2'ca.rbocyanine bromide (0.040) .04 (r) dye (a) (0.015) plus dye (q) (0.040) 11. 8 1. 68 05 30 (3") 1,1'-Diethyl-lO-pheny1-2,2-carbocyanine iodide (0.040) 04 (t' dye (a) (0.015) plus dye (s) (0.040). 4.7 1.8 .05 31 (11' 10-p-chloropheny1-1,1'-d1methyl2,2'carbocyanme 1od1de (0.040) 04 (11) dye (a) (0.015) plus dye (11") (0.040) 5. 2 1. 45 05 32 {(w") 1,1Dimetl1yl-10-(otolyl)2,2carboeyan1ne iodide (0.040) 04 (z) dye (a) (0.015) plus dye (10") (0.040) 9.4 2. 1 .05 33 {(y") 1,1D1ethly10(o-tolyl)-2,2'carbocyan1ne iodide (0.040) 04 (2") dye (a) (0.015) plus dye (9") (0.040) 8.2 2. 2 .O5 3L (am) 1,1'D1ethyl10anaphtl1y1-2.2'carbocyan1ne iodide (0.040) 04 (b'") dye (a) (0.015) plus dye (a"') (0.040) 5. 5 1.9 05 (c") dye (a) (0.030) 8.4 0.53 .05 35 (d) 1',3D1ethyl9phenylth1a2'-carboeyanmeiodide (0.040) 2.5 1.06 .05 (e) dye (a) (0.015) plus dye (d) (0.040) 17. 5 1. 55 .05 36 {(Jm) 1',3-Diethyl-Q--naphthylthia-2-carbocyanine iodide (0.040) 2. 5 0. 96 05 g') dye (a) (0.015) plus dye( (0.040) 12.3 1.56 .05 37 (h"') 1',3Diethyl9(Q-phenanthryl) thia2'carbocyan1ne lodide (0.040) 3. 6 1. 46 05 (i) dye (a) (0.015) plus dye (h.") (0.040) 8.4 1.27 .05 U" dye (j) (0080)-.-- 4. 1 1. 98 .05 38---.- (km) 5[(1-Ethyl-2(1H)-Q-naphthothiazolylidene) (3-methyl-2(3H):d-naphthoxazoly- 6. 8 2.72 .05

l1dene)isopropyl1dene]l,3d1(methoxyethyl)barbiturlc acid (0.080). (Z"') dye (j) (0.080) plus dye (k"') ).080) 21. 5 1. 62 .07 (m"') 5[(1Ethyl-2(1H)-B-naphthothlazolylldene) (3-methyl-2(3H)--naphthoxazoly- 23. 0 1.87 .05 1 ene isopropy ene 1 B-me oxye y ar 1 une :am 39 l'd lid 1 3 d'( th th l)b b't 'd (0 080) ('n."') dye (j) (0.080) plus dye (mm) (0.080) 25. 5 1.73 .08 (o") 5-[(1-Ethyl-2(1H)--naphthothiazolylidene) (Py-methyl2(3H)anaphthothiazol 12. 6 2. 70 .05 40 d yli d13) i %pro pyl i den]-1,5i-1i(-methoxyethybbarbituric acid (0.080). 24

(p ye j pus ye o" 0.0 0 .5 1.29 07 The accompanying drawing illustrates the supersensitizing effect obtained with three of our new combinations of dyes in gelatino-silver-bromiodide emulsions. Each figure of the drawing is a diagrammatic reproduction of two, or in the case of Figure l, three, spectrographs. In each figure, the sensitivity of the emulsion containing the cyanine dye of Formula I (or III) is represented by the solid curve. 'Ihe uppermost curve (broken line) represents the sensitivity conferred on the emulsion by the combination of the cyanine dye of Formula I (or IH) and the un-ionized dye of Formula II (or IV). In Figure 1 the third curve (alternate short and long lines) represents the sensitivity conferred on the emulsion by the un-ionized dye of Formula II (or IV) alone. This third curve has been omitted in Figure 2 inasmuch as it would be identical to the said third curve of Figure 1, while in Figure 3, vthe unionized dye alone had a sensitivity too low to be significant.

In Figure 1, curve A represents the sensitivity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 3,3'-diethyl-9phenylthiacarbocyanine iodide, curve B represents the sensitivity of the same emulsion containing 1,3 diethyl-S-[di(1-ethyl-Z(1H)naphthothiazolylidene)isopropylidene] barbituric acid, and curve C represents the sensitivity of the same emulsion containing both 3,3'diethyl-9-phenylthiacarbocyanine iodide and 1,3 diethyl 5 [di(1 ethyl 2(1H) napthothiazolylidene)isopropylidene]barbituric acid. The sensitometric measurements for these emulsions are given in Example 1 of the above table.

In Figure 2, curve D represents the sensitivity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 3,3 dimethyl 9 phenyl 4,5,4,5' dibenzothiacarbocyanine bromide. Curve E represents the sensitivity of the same emulsion containing both 3,3dimethyl 9 phenyl 4,5,4,5 dibenzothiacarbocyanine bromide and 1,3 diethyl 5 [di(l ethyl- 2(1H) napthothiazolylidene)isopropylidenelbarbituric acid. The sensitometric measurements for these emulsions are given in Example 5 of the above table.

In Figure 3, curve F represents the sensitivity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 3,3 diethyl 9 (3 pyrrl) 4,5,4',5 dibenzothiacarbocyanine bromide and cuive G represents the sensitivity of the same emulsion containing both 3,3- diethyl 9 (3 pyrrl) 4,5,4,5' dibenzothiacarbocyanine bromide and 1,3-diethy1-5-[di(l-ethyl-Z(lH)- naphthothiazolylidene) isopropylidene] barbituric acid. The sensitornetric measurements for these emulsions are given in Example 18 of the above table.

Our invention is primarily directed to the ordinarily employed gelatino-silver-halide developing-out emulsions,

e. g. gelatino-silver-chloride, chlorobromide, -chloroioand at least one dye selected from those represented by dide, -chlorobromiodide, -bromide and -bromoiodide dethe following general formula:

veloping-out emulsions. While the results in the above .tables were obtained using gelatino-silver-bromiodide ,'ZN /Z\ emulsions, excellent results have also been obtained us- Ra- =CHC==CH-6 -Rr ing gelatino-silver-chlorobromide emulsions. Emulsions 9 which form the latent image mostly inside the silver halide grains, such as the emulsions set forth in U. S. -oe

Patent 2,456,956, dated December 21, 1948, can also be employed in practicing our invention. 10 wherein R3 and R4 each represents an alkyl group, Z2 The emulsions prepared in accordance with our inrepresents the non-metallic atoms necessary to complete vention can be coated in the usual manner on any suita heterocyclic nucleus selected from the group consisting able support, e. g. glass, cellulose nitrate film, cellulose of those of the benzothiazole series, those of the naphacetate lm, polyvinyl-acetal resin lm, paper or metal. thotliiazole series, those of the benzoselenazole series, Photographic silver halide emulsions, such as those those of the naphthoselenazole series, and those of the listed above, containing the supersensitizing combinations naphthoxazole series, Za represents the non-metallic atof our invention can also contain such addenda as chemoms necessary to complete a heterocyclic nucleus seical sensitizers, e. g. sulfur sensitizers (e. g. allyl thiolected from the group consisting of those of the naphcarbamide, thiourea, allylisothiocyanate, cystine, etc.), thothiazole series and those of the naphthoselenazole various gold compounds (e. g. potassium chloroaurate, series, and Q represents the non-metallic atoms necessary auric trichloride, etc.) (see U. S. Patents 2,540,085; to complete a nucleus selected from the group consisting 2,597,856 and 2,597,915), various palladium compounds, of those of the indandione series, those of the barbituric such as palladium chloride (U. S. 2,540,086, potassium acid series, those of the 2-thiobarbituric acid series, and chloropalladate (U. S. 2,598,079), etc., or mixtures of those of the isoxazolone series.

such sensitizers; antifoggants, such as ammonium chlo- 2. A photographic gelatino-silver-bromiodide emulroplatinate (U. S. 2,566,245), ammonium chloroplatision sensitized with a supersensitizing combination of at nite (U. S. 2,566,263), benzotriazole, nitrobenzimidazole, least one carbocyanine dye selected from those repre- S-nitroindazole, benzidine, mercaptans, etc. (see Meessented by the following general formula:

fr R1 i v-* f R-N (--CH=CH) i-TSC H-=CH-C (20H- CID .i=l\|T-Ri The Theory of the Photographic Process, Macmillan wherein R and Ri each represents an alkyl group con- Pub., page 460), or mixtures thereof; hardeners, such as taining from 1 to 2 carbon atoms, R2 represents a monoformaldehyde (U. S. 1,763,533), chrome alum (U. S. nuclear aromatic group of the benzene series, m and n 1,763,533), glyoxal (U. S. 1,870,354), dibromacrolein each represents a positive integer of from 1 to 2, X (Br. 406,750), etc.; color couplers, such as those derepresents an acid radical, and Z and Zi each represents scribed in U. S. Patent 2,423,730, Spence and Carroll the non-metallic atoms neessary to complete a hetero- U. S. application 771,380, led August 29, 1947, now cyclic nucleus selected from the group consisting of those Patent No. 2,640,776, etc.; or mixtures of such addenda. of the thiazole series, those of the benzothiazole series, Dispersing agents for color couplers, such as those Set those of the naphthothiazole series, those of the benzoforth in U. S. Patents 2,322,027 and 2,304,940, can also selenazole series, those of the naphthoselenazole series, be employed in the above-described emulsions. those of the benzoxazole series, those of the naphthox- In the above table it will be noted that in certain eX- azole series, those of the 2-quinoline series, and those of amples the amounts of dyes used in the supersensitizthe 4-quinoline series, and at least one dye selected from ing combinations do not corresepond to the amounts used those represented by the following general formula: with each dye alone. Actually, supersensitization oc- ZA ,Z3 curs according to our invention when the combination of ,f f dyes gives more speed than either dye alone at any con- R:N C=CHC=CH6 N-Ri centration. Thus, in some instances, the amount of dye, E when used alone, is not identical with that used in the ,1' X e supersensitizing combination. This is due to the fact 'that Q -0 optimum conditions have been used, insofar as possible, wherein R3 and R4 each represents an alkyl group con- 11 each 0f the QQamgS Ue O f larger amounts of dyes 55 taining from 1 to 2 carbon atoms, Z2 represents the {Il the supel'sensmzmg Combmatlons 1,5 not necessary and non-metallic atoms necessary to complete a heterocyclic 1D Some mstals: 1S ac tuauy, detrlmemalnucleus selected from the group consisting of those of what We Claim as our ,invention aPd dem@ Secured by the benzothiazole series, those of the naphthothiazole Letters Patent 0f the Ullled StaeS 151 series, those of the benzoselenazole series, those of the 1- A Photographie Silver hande emlllSlOIl SeIlSlflZed 60 naphthoselenazole series, and those of the naphthoxazole with a supersensitizing combination of at least one carboseries, Z3 represents the non-metallic atoms necessary to cyanine dye selected from those represented by the folcomplete a heterocyclic nucleus selected from the group lowing general formula: consisting of those of the naphthothiazole series and those of the naphthoselenazole series, and Q represents the Whereln R and R1 each represente all alkyl glOUP, R2 70 nonmeta1lic atoms necessary to complete a nucleus serepresents a member selected from the group consisting eicted from ttlle groufp lzorjsistling of thtse of thehindan ym, X t one series, o se o' t e .ar ituric aci series, t ose o of.an alyl group and a p 1 group rpfese? s an Vthe thiobarbituric acid series, and those of the isoXazoacid radical, m and n each represents a positive integer lone Series. of from l to 2, and Z and Z1 each represents the non-me- 75 3, A photographic g1?tin0.si1ver.ha1ide emulsion tallic atoms necessary to complete a heterocyclic nucleus sensitized with a supersensitizing combination of at least containing from 5 to 6 atoms in the heterocyclic ring, one cal'boyanme dye Selected from those represented by `.the following general formula:

B: Zi

lux-o9 wherein R3 and R4 each represents an alkyl group conmetallic atoms necessary to complete a heterocyclic nucleus selected from the group Vconsisting of those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, and those of the naphthoxazole series, Z3 represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the naphthothiazole series and those of the naphthoselenazole series, and Q represents the non-metallic atoms necessary to complete a nucleus selected from the group consisting of those of the indandione series, those of the barbituric acid series, those of the thiobarbitun'c acid series, and those of the isoxazolone series.

6. A photographic gelatino-silver-bromiodide emulsion sensitized with a supersensitizing combination of at least one carboncyanine dye selected from those represented by the following general formula:

taining from 1 to 2 carbon atoms, Zz represents the nonmetallic atoms necessary to complete a heterocyclic neucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, and those of the naphthoxazole series and Q represents the non-metallic atoms necessary to complete a nucleus selected from the group consisting of those of the indandione series, those of the barbituric acid series, those of the thiobarbituric acid series, and those of the isoxazolonc series.

4. A photographic gelatino-silver-halide emulsion as delned in claim 3 wherein Z2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series.

5. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one carbocyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group conf taining from 1 to 2 carbon atoms, R5 and Rs each represents a member selected from the group consisting of a hydrogen atom, an alkyl group containing from l to l2 carbon atoms, and an aryl group containing from 6 to 7 carbon atoms, Z4 represents the'non-metallic atoms necessary to complete a pyrryl nuclues, m and n each represents a positive integer of from 1 to 2, X represents an acid radical, and Z and Z1 each represents the nonmetallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole sexies, those of the benzoxazole series, those of the naphthoxazole series, those of the 2-quinoline series, and those of the 4quino wherein R and R1 each represents an alkyl group containing from 1 to 2 carbon atoms, Rs and Re each represents a member selected from the group consisting of a hydrogen atom, an alkyl group, and an aryl group, Z4 represents the non-metallic atoms necessary to complete a pyrryl nucleus, m and n each represents a positive integer of from l to 2, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the 2quinoline series, and those of the 4-quinoline series, and at least one dye selected from those represented by the following general formula:

J/Z2\` zh ,o c---E-oe wherein R3 and R4 each represents an alkyl group containing from 1 to 2 carbon atoms, Za represents the nonline series, and at least one dye selected from those represented by the following general formula:

wherein Ra and R4 each represents an alkyl group containing from 1 to 2 carbon atoms, Z2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the lbenzothiazole series, those of the naphthothiazole series,

metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series.

8. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one carbocyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group of the formula CnHzn+1 wherein n represents a positive integer of from 1 to 2, R2 represents a mononuclear aromatic group of the benzene series, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and at least one dye selected from those represented by the following general formula:

wherein R3 and R4 each represents an alkyl group of the formula CmHzmt-i wherein m represents a positive integer of from 1 to 2, L represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and Q represents the non-metallic atoms necessary to complete a nucleus of the barbituric acid series.

9. A photographic gelatino-silver-bromiodide emulsion sensitized with a supersensitizing combination of 3,3'dimethyl 9 phenyl- 4,5,4,5 dibenzothiacarbocyanine bromide and 1,3-diethyl5-[di(1ethyl-2(1H) naphthothiazolylidene) isopropylidene] barbituric acid.

10. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one carbocyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group of the formula CnH2n+1 wherein n represents a positive integer of from 1 to 2, R2 represents a mononuclear aromatic group of the benzene series, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and at least o ne dye selected frag those represented by the following general form wherein R3 and R4 each represents an alkyl group of the formula CmHzm-t-i wherein m represents a positive 1nteger of from 1 to 2, Zz represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series, and Q represents the nonmetallie atoms necessary to complete a nucleus of the Z-thiobarbituric acid series.

11. A photographic gelatino-silver-bromiodide emulsion sensitized with a supersensitizing combination of 3,3' dimethyl- 9 phenyl- 4,5,4,5'dibenzothiacarbocy anine bromide and 1,3-diethyl-5[(3ethyl2(3H)-benzothiazolylidene) l-methyl 2( 1H)naphthoselenazoly1 idene)isopropylidenel-2-thiobarbituric acid.

12. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least Cil one carbocyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group of the formula CnHznH wherein n represents a positive integer of from l to 2, R2 represents a mononuclear aromatic group of the benzene series, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and at least one dye selected from those represented by the following general formula:

wherein Rs and R4 each represents an alkyl group of the formula CmH2m+i wherein m represents a positive integer of from 1 to 2, Z3 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthoselenazole series, and Q represents the nonrnetallic atoms necessary to complete a nucleus of the 2-thiobarbituric acid series.

13. A photographic gelatino-silver-bromodide emulsion sensitized with a supersensitizing combination of 3,3 dimethyl 9 phenyl- 4,5,4',5dibenzothiacarbocy anine bromide and 5[(3-ethyl-2-(3H)it-naphthothiazolylidene) (1 ethyl-2(1H)--naphthothiazolylidene)isopropylidene] -l-methyl-Z-thiobarbituric acid.

14. A photographic gelatino-silver-bromiodide emulsion sensitized with 3,3'-dimethyl-9-phenyl-4,5,4,5'dibenzo thiacarbocyanine bromide and 5[di(1ethyl2(lH)- naphthothiazolylidene)isopropylidene] 1,3 dim-methoxyethyl) barbituric acid.

15. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one carbocyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group of the formula CnH2n+1 wherein n represents a positive integer of from l to 2, R2 represents a pyrryl group, X represents an acid radical, and Z and Z1 each represents the nonmetallic atoms necessary to complete a heterocyclic nucleus of the naphthoxazole series, and at least one dye electlzleld from those represented by the following general orm a:

wherein R3 and R4 each represents an alkyl group of the formula CmHzm-t-i wherein m represents a positive integer of from 1 to 2, Za represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and Q represents the non-metallic atoms necessary to complete a nucleus of the indandione series.

16. A photographic gelatine-silver-bromiodide emulsion sensitized with a supersensitizing combination of 3-ethyl3'-methyl-9-(2-methyl 3 indolyl) 4,5,6,7di benzooxacarbocyanine perchlorate and 2[di(1ethyl 2(1H) naphthothiazolylidene)isopropylidenel 1,3- indandione.

No references cited. 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION SENSITIZED WITH A SUPERSENSITIZING COMBINATION OF AT LEAST ONE CARBOCYANINE DYE SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 